Fire extinguisher



Dec. l2, 1933.

C. B. WHITE FIRE EXTINGUISHER Filed Feb. 3. 1931 Patented Dec. l2, 1933 v PATENT OFFICE FIRE EXTINGUISHER Clifford B. White, Elmira, N. Y., assignor to American-La France and Foamite Corporation, New York, N. Y., a corporation of New York Application February 3,

. Claims.

In theV maintenance of soda-acid fire extinguishers considerable Vdifficulty is experienced from the breaking of the modern machine-made bottles now in general use. In these extinguish- 5 ers the acid,- usually sulphuric, is held in a glass bottle withinV a container holding'a basic solution usually sodium bicarbonate. The extinguisher is operated by setting it on its head, whereupon the acid is intended to flow gradually or meter out of the bottle to react with the' soda, raising the internal pressure in the extinguisher gradually to a maximum of some ninety pounds, which expels the liquid contents out through the hose. If the bottle breaks during operation an excessive quantity of acid is released suddenly (as distinguished from metering) causing a sudden and excessive pressure to be developed within the extinguisher shell which is undesirable. The sudden release of acid is also liablev to cause the extinguishing stream to become momentarily acid which is very undesirable. In addition to these undesirable operating characteristics caused by the breakage of the bottlethere is Valso to be considered the wastage due to breaking and the danger to the operator from slivers of glass when the extinguisher is cleaned out and recharged. If the slivers of glass are not removed they may cause clogging of the outlet.

Because of its cheapness and chemical innertness glass is the preferred material for the acid container in spite of its fragility. It is quite possible to reduce or eliminate this breakage by using a special glass, but the expense of so doing is not warranted. Eiorts have been made to reduce the breakage by changing the design of the bottles and by changing the thickness of the glass but these have not been entirely successful and the percentage of breakage still continues high.

I have discovered a means of practically eliminating such breakage whichis simple, inexpensive, and highly effective. It consists in coating the bottle, or a portion of it, with wax, such for example as a wax made of a mixture of beeswax and rosin or parailin, or the like.

The accompanying drawing shows in Fig. 1 the type of extinguisher referred to, and in Fig. 2, a longitudinal section of the wax-coated bottle and Fig. 3 shows the bottle ready for shipv ment containing the acid. Y l

The coating may be applied by dipping the bottle in the melted wax. Covering the neck and yshoulders of the bottle, about as indicated in Fig. 2, is sufficient and the shoulder portion should in any event be covered. In Fig. 2, the

1931. Serial No. 513,104

Wax coating is indicated at 1 and the bottle is shown in this figure with its usual lead stopper 2 in place. This stopple, it will be understood, falls out when the extinguisher is inverted.

I Iind it most practical to apply the wax coating to the bottle after it has been lled with its charge of acid and corked for shipment in which case the cork or seal 3 is also covered over with the wax `and thereby additionally sealed and secured in place, as indicated in Fig. 3. When the bottle is put into the extinguisher the wax covering over the cork or seal is removed, the bottle is opened and the usual lead stopper inserted. The wax in this case serves the dual purpose of securing the seal prior to use and thereafter of preventing breakage and on subsequent re- Iillings by the customer or user it continues to guard against breakage as long as the'wax remains in place.

The principle by which this effect is produced is the prevention of a sharp heat gradient across the thickness of the glass wall. I have ascertained that the breakage occurs primarily from this cause and that this results from the heat of a chemical reaction taking place inside of the bottle itself. On inversion, the acid falls or ows out of the bottle into the surrounding basic solution and some of the latter, as yet unneutralized, gulps back into the bottle to take the place of the departed portion of acid. The exothermic reaction makes the inside surface of the glass wall much hotter than the outside surface, which is now in contact with the large mass of cooler liquid of the basic solution, and the resultant difference of thermal expansion, together with the pressure and the possible rjarring of the extinguisher, accounts for the breakage. The coating of wax forms or produces a heat barrier, thereby establishing a more uniform temperature through the thickness of the glass wall than would otherwise be the case, and this is sufiicient to prevent breakage. It is applied only to the neck and shoulders or top part of the bottle, because this is the region where breakage occurs, due to the fact possibly that the bottle is only partially filled withY acid and the uppermost part contains only air when the extinguisher is in action. Other forms of heat barrier associated with or applied either to interior or exterior surface have the same effect and may be equally efficient, though perhaps not so easily appliedA or basket 4 secured to the cap or the neck-opening of the container in any desired way and as conventional indicated by the drawing.

I claim:

1. In a fire extinguisher Yof the type in which chemical reagents, contained in separate compartments and one of them in a glass receptacle or bottle, react on discharge of the extinguisher to produce expelling gas pressure with evolution of heat; the means for preventing bottlefracture which consists in combination with said bottle, of a covering for the wall thereof, said covering being of a material and `thickness adapted to prevent a sharp /heatgradientthrough said Wall due to the reaction heat.

2. In a fire extinguisher of the type in which rchemical reagents, contained in separate Vcompartments, one of them in a glass receptacle or bottle, react on discharge of the extinguisher to produce expelling gas pressure with evolution of lheat; the means of avoiding bottle-fracture which consists .in the combination with said .bottle of -an adherent coating on the body of the bottle protecting it against fracture from a too sharp heatlgradient through thewall thereof due to the reaction heat.

S3. `=In a fire extinguisher of .the type inwhich chemical reagents, contained in `separate compartments,A one of them in a glass receptacley or bottle,react on discharge of theextinguisher to produce expellingrgas zpressure vwithevolution of heat; the means of preventing bottle-fracture which consists, in combination with said bottle, of a covering applied only to the neck and shoulder portions thereof and adapted to prevent a too sharp heat gradient through the bottle Wall due to the reaction heat.

4. Inka soda and acid fire extinguisher, a main compartment containing the soda-solution, an open bottle cage supported therein, a glass bottle supported in said cage containing acid and fadapted to be submerged in said soda solution when the extinguisher is set in action, and means for preventing fracture of said bottle comprising a heat barrier associated therewith adapted to rprevent a sharp heat gradient through the bottle wall due to the heat evolved by the reaclili) 

